Three-dimensional information can also be referred to depth information or depth of field information. The traditional method of image capture can only obtain the two-dimensional information of an object and can not obtain the spatial depth information of an object, however, the spatial depth of object surface information, especially obtaining the depth information in real-time, plays a crucial role in a variety of industrial, daily and entertainment applications.
The existing depth detection apparatus generally uses an auxiliary discrete light source, such as structured light, for illumination, and calculates the depth information of the surface of the measured object by detecting the phase shift of the structured light. In brief, first, a two-dimensional laser texture pattern with coded information, such as a discrete speckle pattern, is projected onto the surface of the object to be measured, and another image capturing device with a relatively fixed position continuously acquires the laser texture. The processing unit then compares the acquired laser texture sequence with a reference surface texture sequence of a known depth distance pre-stored in a memory to calculate the depth distance of each laser texture sequence segment projected on the surface of the object, and further obtains the 3D data of the surface of the object to be measured. The three-dimensional measurement technique based on this structured light detection uses the method of parallel image processing, which can detect the depth information of the object to be detected to a certain extent.
However, the existing apparatus for detecting depth still has several deficiencies. First, the relative position of the laser and the image capturing device needs to be calibrated by acquiring the reference surface multiple times. Since the laser is a consumable element, once the laser is damaged and replaced, the relative position of the laser and the image capturing device needs to be calibrated, which will increase the equipment maintenance costs. Second, as the device operates with a single laser, when continuously measured over a long period of time, the aging of the laser will accelerate, far beyond the normal lifetime of the laser (typically, the lifetime of the laser is from 10,000 to 20,000 hours), thus shortening the service life of the equipment, increasing the equipment maintenance cost and reducing the feasibility of the deep data detection apparatus applied in the field which long-time reliable operation is needed, such as security monitoring. Third, the device can only detect the depth data at the position where the texture segment exists on the object to be detected, but can not accurately obtain the depth data at the position where the texture segment is not projected on the object to be detected. Lastly, for security monitoring applications, the intensity of the light projected by the lighting system to the monitoring space that is far away is weaker, so that the distance that can be monitored is limited. Increasing the power of the lighting system will in turn cause energy waste and increases costs.
Therefore, there is a need for improved depth data detection and monitoring apparatus.